Creatine supplements are athletic aids used to increase high-intensity athletic performance. Though researchers have known of the use of creatine as an energy source by skeletal muscles since the beginning of the 20th century, they were popularized as a performance-enhancing supplement in 1992.
History of creatine supplements
In 1912, researchers found that ingesting creatine can dramatically boost the creatine content of the muscle. In the late 1920s, after finding that the intramuscular stores of creatine can be increased by ingesting creatine in larger than normal amounts, scientists discovered creatine phosphate, and determined that creatine is a key player in the metabolism of skeletal muscle.
While creatine's influence on physical performance has been well documented since the early twentieth century, it only recently came into public view following the 1992 Olympics in Barcelona. An August 7, 1992 article in The Times reported that Linford Christie, the gold medal winner at 100 meters, had utilized creatine prior to the Olympics, and an article in Bodybuilding Monthly named Sally Gunnell, gold medalist in the 400-meter hurdles, as another creatine user. Several medal-winning British rowers also used creatine during their preparations for the Barcelona games.
Another important event in creatine supplementation occurred in 2004 when the first creatine ethyl ester supplements were launched. Creatine ethyl ester (CEE) is becoming a widely used form of creatine, with many companies now carrying both creatine monohydrate-based supplements and CEE supplements, or combinations of both.
Creatine and athletic performance
Creatine is often taken by athletes as a supplement for those wishing to gain muscle mass (bodybuilding). There are a number of forms but the most common are creatine monohydrate - creatine bonded with a molecule of water, and Creatine ethyl ester (CEE). A number of methods for ingestion exist - as a powder mixed into a drink, or as a capsule or caplet. Once ingested, creatine is highly bioavailable, whether it is ingested as the crystalline monohydrate form, the free form in solution, or even in meat. Creatine salts will become the free form when dissolved in aqueous solution. With studies repeatedly reporting an upper maximal range for muscular creatine concentration, it is unlikely that the form of creatine ingested results in increased or altered final gains. Conventional wisdom recommends the consumption of creatine with high glycemic index carbohydrates, though research indicates that the use of high GI carbs in combination with protein is also beneficial.
Some studies have shown that creatine supplementation increases both total and fat-free body mass, though it is difficult to say how much of this is due to the training effect. Since body mass gains of about 1 kg can occur in a week's time, many studies suggest that the gain is simply due to greater water retention inside the muscle cells. However, studies into the long-term effect of creatine supplementation suggest that body mass gains cannot be explained by increases in intracellular water alone. In the longer term, the increase in total body water is reported to be proportional to the weight gains, which means that the percentage of total body water is not significantly changed. The magnitude of the weight gains during training over a period of several weeks argue against the water-retention theory.
Also, research has shown that creatine increases the activity of satellite cells, which make muscle hypertrophy possible. Creatine supplementation appears to increase the number of myonuclei that satellite cells will 'donate' to damaged muscle fibers, which increases the potential for growth of those fibers. This increase in myonuclei probably stems from creatine's ability to increase levels of the myogenic transcription factor MRF4.
In another study, researchers concluded that changes in substrate oxidation may influence the inhibition of fat mass loss associated with creatine after weight training when they discovered that fat mass did not change significantly with creatine but decreased after the placebo trial in a 12-week study on ten active men. The study also showed that 1-RM bench press and total body mass increased after creatine, but not after placebo.
Creatine use is not considered doping and is not banned by the majority of sport-governing bodies. However, in the United States, the NCAA recently ruled that colleges could not provide creatine supplements to their players, though the players are still allowed to obtain and use creatine independently. In some countries, such as France, creatine is banned.
Creatine ethyl ester
CEE is a form of commercially available creatine touted to have higher absorption rates and a longer serum half-life than regular creatine monohydrate by several supplement companies. No peer-reviewed studies have emerged on Creatine ethyl ester to conclusively prove these claims.
As a supplement, the compound was developed, patented and licensed through UNeMed, the technology transfer entity of the University of Nebraska Medical Center.
Current studies indicate that short-term creatine supplementation in healthy individuals is safe. Small-scale, longer-term studies have been done and seem to demonstrate its safety. There have been reports of muscle cramping with the use of creatine, though a study showed no reports of muscle cramping in subjects taking creatine-containing supplements during various exercise training conditions in trained and untrained endurance athletes.
Creatine and mental performance
Creatine administration was shown to significantly improve performance in cognitive and memory tests in vegetarian individuals involved in double-blind, placebo-controlled cross-over trials. Vegetarian supplementation with creatine seems to be especially beneficial as they appear to have lower average body stores.
Greenhaff PL et al. (1993). "Influence of oral creatine supplementation on muscle torque during repeated bouts of maximal voluntary exercise in men.". Clinical Science 84: 565-571. PMID 8504634. .